Catalysts for the polymerization of olefins

ABSTRACT

NEW CATALYSTS FOR THE POLYMERIZATION OF OLEFINS ARE DISCLOSED. THE CATALYSTS ARE PREPARED BY CONTACTING AN ALCOHOLIC COMPOUND CONTAINING ONE OR MORE HYDROXY GROUPS WITH DELTA TITANIUM TRICHLORIDE UNDER CONDITIONS SUCH THAT AT LEAST 1% AND PREFERABLY 20%, OF THE FINE POWDERS HAVING A PARTICLE SIZE SMALLER THAN 20 MICRONS, NORMALLY PRESENT IN THE TRICHLORIDE, DISAPPEAR, AND THEN MIXING THE RESULTING PRODUCT WITH AN ALKYL ALUMINUM COMPOUND. ALSO DISCLOSED IS THE USE OF THE NEW CATALYSTS IN THE POLYMERIZATION OF PROPYLENE, BUTENE-1, 4-METHYLPENTENE-1 AD SIMILAR ALPHA-OLEFINS TO HIGHLY ISOTACTIC POLYMERS CHARACTERIZED BY A VERY NARROW GRANULOMETRIC DISTRIBUTION, A LOW CONTENT OF FINE POWDERS, AND A HIGH BULK DENSITY.

United States Patent Oflice 3,793,295 Patented Feb. 19, 1974 US. Cl. 26093.7 13 Claims ABSTRACT OF THE DISCLOSURE New catalysts for the polymerization of olefins are disclosed. The catalysts are prepared by contacting an alcoholic compound containing one or more hydroxy groups with delta titanium trichloride under conditions such that at least 1% and preferably 20%, of the fine powders having a particle size smaller than 20 microns, normally present in the trichloride, disappear, and then mixing the resulting product with an alkyl aluminum compound. Also disclosed is the use of the new catalysts in the polymerization of propylene, butene-l, 4-methylpentene-1 and similar alpha-olefins to highly isotactic polymers characterized by a very narrow granulometric distribution, a low content of fine powders, and a high bulk density.

PRIOR ART Catalysts for the polymerization of olefins and prepared by mixing alkyl aluminum compounds, particularly dialkyl aluminum monohalides, with delta titanium trichloride obtained by dry-milling alphaand/or gammatitanium trichloride are known.

Said catalysts are highly active in the polymerization of the higher alpha-olefins and effect the polymerization stereo-specifically. However, the polymers formed often do not have a very high bulk density and generally comprise a considerable amount of fine powders the particles of which have sizes smaller than 100 microns.

The presence of the fine powders in the polymers produced on an industrial scale, together with relatively low values of the bulk density, can give rise to problems in the processing of the polymers, which problems, if not overcome, result in a reduction in the productivity of the equipment. In fact, the fine powders tend to clog the centrifuges in which the polymer is separated from the polymerization slurry, and impede feeding of the polymer to the drawbenches for granulation.

The difficulties arise, for the most part, from the fact that the delta titanium trichloride used heretofore in preparing the catalysts has a very wide granulometric distribution and a high content, in many cases exceeding 70% or more, of fine powders the particles of which are smaller than 20 microns in size.

Various methods have been proposed for obviating the problems mentioned, with, however, less than satisfactory results.

For instance, it is possible to remove the fine powders by screening the delta TiCl but the coarser fractions thus separated tend to scale, and consequently can again give rise to fine powders.

Moreover, in order to remove the fine powders, it was always proposed (see Belgian Pat. No. 655,308) to prepare the delta TiCl by dry-milling alpha and/or gamma TiCl in the presence of small quantities of ketones or ethers.

The results obtained by that method are not very satisfactory.

According to the Belgian patent it is absolutely necessary to add the ketones or ethers during the milling step, and not after the milling step has been completed.

This is due to the fact that if the ketones or ethers are added after the milling step, the content of particles of fine size is not decreased, but there is a tendency to lowering of both the activity and stereospecificity of the catalyst prepared from the resulting TiCl The requirement for addition of the ketones or ethers before or during the milling step means that the fine powders will not be removed elfectively, since the fine powders are formed continuously during the milling.

Furthermore, both the ketones and ethers, whether used before, during, or after the milling operation, have little or no effect on the bulk density of the polymers obtained.

If the ketones and ethers are used during the activa tion phase of titanium trichloride they tend to lower the catalytic activity and the product obtained shows a strong tendency to scaling off of the crystalline aggregates which is most apparent during the step of premixing the catalyst-forming components.

THE PRESENT INVENTION One object of this invention is to provide new catalysts for the polymerization of olefines which avoid many of the above-mentioned problems.

This and other objects are accomplished by the invention which provides new catalysts prepared by mixing.

(a) an alkyl aluminum compound having the formula AlR or R AlX, in which R is an alkyl radical containing from 2 to 6 carbon atoms and X is halogen, with (b) the product containing titanium trichloride in the delta crystalline form, said product being obtained by homogenizing an alcoholic compound containing one or more hydroxy groups with a preformed delta titanium trichloride prepared by dry milling alpha and/or gamma TiCl or compositions consisting of alpha and/ or gamma TiCl cocrystallized with AlCl or by carrying out the homogenization during the formation of delta titanium trichloride by dry milling alpha and/0r gamma trichloride, or compositions consisting of alpha and/or gamma TiCl cocrystallized with AlCl in the presence of the alcoholic compound and in the absence of inert solvents, under conditions such that at least a portion, and preferably 20%, of the fraction of titanium trichloride having a particle size smaller than 20 microns disappears.

The delta crystalline TiCl can be pre-formed by drymilling alpha and/or gamma TiCl or compositions consisting of alpha and/or gamma TiCl cocrystallized with AlCl Or the delta titanium trichloride may be contacted with the alcoholic compound as it is formed during the milling step.

Representative alcoholic compounds which are suitable for use in practicing the invention include monoand polyhydric aliphatic :alcohols containing from 1 to 10 carbon atoms, such as methanol, ethanol, propanol-l, propanol-Z, but-anol-l, Z-ethyI-butanol-l, butanol-Z, 2- ethyl-hexanol-l, 3-methyl-hexanol-1, S-methyl-hexanol-Z, heptanol-3, pentaerythritol, glycerol, ethylene glycol.

Further examples of suitable alcoholic compounds are furfurol, phenylcarbinol and alpha-alpha'-diisopropylbenzenediol.

Besides the hydroxy group, the compounds which may be used may contain other organic functions or substituent groups. Examples of these last-mentioned compounds are glycolmonoalkylethers and glycolmonoarylethers such as, for instance, diethyleneglycol-mono-butylether, diethylene-glycol-monophenylether, 4 hydroxy 4 methylpentanone-Z (diacetone alcohol), 2,3-dichloropropanol-1 etc.

The catalytic component (b) can be prepared in various ways. The preferred method consists in homogenizing the starting delta titanium trichloride and the alcoholic a period of time and using amounts of alcoholic compound sufi-icient to obtain the reduction of the content in fine powders of the starting titanium trichloride.

Alternatively, instead of homogenizing the delta TiCl the other hand, the latter catalysts are, in general, somewhat less active.

The Al/Ti ratio used in the preparation of the catalyst is generally higher than 1. In the case of the propylene polymerization it is preferably comprised between 1 and 3.

and alcoholic compound in the dry state, that is in the 5 The polymerization of the alpha-olefins with the cataabsence of solvents the homogenizing may be carried out lysts of the present invention is carried out according to in an inert solvent such as, for example, the hydrocarbon the known methods, operating in liquid phase, in the solvent to be used in the polymerization of the alphapresence, or in the absence, of inert diluents, or in the olefins in contact with the catalyst. gaseous phase.

Generally, the homogenizing is carried out at room tem- The polymerization temperature is generally comprised perature. However, it is possible to operate also at lower between -80 and 200 C., preferably between 50 and or higher temperatures, taking into consideration that in 100 C. The process is carried out at atmospheric pressure this latter case, it is not convenient to exceed the temperaor under pressure. ture of 90-100 C. above which there is a deterioration The molecular weight of the polymer is adjusted accordof the catalytic properties and stereospecificity of delta ing to the known methods, for example by including alkyl titanium trichloride. halides, hydrogen, Zn-alkyls and similar regulators of the The reaction between delta titanium trichloride and the molecular weight in the polymerization zone. alcoholic compound is an exothermic reaction. It is advis- The following examples are given to illustrate the invenable in some cases, especially when considerable quantities tion and are not intended to be limiting. of trichloride are treated, to remove the reaction heat.

Another method for preparing component (b) of these Example 1 catalysts consists, as has been indicated, in eflecting the milling of alpha and/or gamma titanium trichloride to 3 a 4 autoclave proYlded with a stirrer and (iondelta trichloride in the presence of the alcoholic comtalmflg 18001111 of np ane dried on sodium Pound. This is not the presently preferred method hydride werefed 1.1 g. of delta titanium trrchlonde having The quantity of alcoholic compound used in practicing the composition 3T 1Cl -A lCl obtalned by the reductlonat the invention is, in general, lower than 20% by Weight 150-160 C. of T1Cl w1th Al 1n stochiometric quantity with respect to the starting delta titanium trichloride. i subseqlient transfmtaim of the reducnon product Good results were obtained using the alcoholic compound Into delta T1013 by l i in an amount of from 2 to 10% by Weight with respect to The granulometrlc distribution curve of tltanrum tnthe titanium trichloride chloride thus obtained shows that 60% of the product The delta trichloride is obtained by dry-milling of alpha 33 332 powders havmg a pamcle SlZe lower than 22 32 mamum mchlmlde the 35 4.7 g of Al(C H Cl were introduced and the catalyst The characteristics of the delta titanium trichloride thus uspenslon then mamtafned under surfing for 1 hour Obtained, and those of the corresponding alpha and m order to lncrease the possible crush of the agglomerates gamma forms f Ticls, are described in Journal Polymer of tltanium tnchlorlde. The temperature was then brought science 5 (1961) to 70 C. Immediately thereafter, a mixture of propylene Alpha titanium trichloride is obtained, according to the and y g f a g -5 N1. of hydrogen per kg. of known methods, by h reduction f Tic}4 with hydrogen propylene was mtroduced to a total pressure of 5 atms. at high temperatures, or by the reduction of rici, with T propylene p s was maintained constant y feedaluminum. Gamma titanium trichloride is obtained by the mg P py centmueusly durmg the pelymerlzahehreduction of TiCl with A1 at temperatures lower than After 4 o h n w n rr p d and the s li 130 140 C. Whe th r d ti i i d out at product was recovered by cold filtrations, and subsequent peratures ranging from about 140 to 200 C., then mixstripping with steam and drying in a stove at 60 C., under tures of alpha and gamma titanium trichloride are formed. nitrogen. The isotacticity degree, the bulk density and the Titanium trichloride obtained by the reduction of TiCl granulometric distribution of the polymer obtained were with aluminum has, in general, the composition 3TiCl determined and are reported in Table l which also con- AlCl tains data relevant to Examples 2-4.

TABLE 1 Granulometric distribution in microns Percent Isotac- (percent by weight) Percent in Apparent on the Catalytic ticity powder, density, Example Type of additive catalyst activity 1 index 21,000 2420 2177 105 274 253 553 3105a kg./l. 38 91.5 12.1 20.3 18.5 13.3 13.2 11 8.6 32.8 0.48 Butanol-l 5 42 95 11.5 20.8 26.5 18.0 6 10.2 7 23.2 0.54 2-ethyl-hexano1-L- 3 45 94.5 18 24.8 32 10 5.1 5.3 4.8 15.2 0.55 Ethyl-phenyl ether 4 38 93.5 0.2 4.2 31 33.4 18 8.5 5.3 31.8 0.40

(C8H5O-C2H5) 1 Catalytic activity expressed in g. polymer/g. 3Ti Cla-AlCla 1 hr. ata. Ct". Gamma titanium trichloride may be obtained by heat- Example 2 ing a beta TiCl prepared by the reduction of TiCl, with hydrogen in the presence of silent discharges, at a temperature of 200 C. or higher.

Examples of alkyl aluminum compounds which can be used as component (a) of the present catalysts include:

Example 1 was repeated except that 5% by weight of butanol-l was added to the delta titanium trichloride. The addition and the homogenization of alcohol with the titanium trichloride was carried out in a centrifugal mill of Locke type for 30 minutes. The content in fine powders with a particle size lower than 20 microns, of the delta 3 TiCl .AlCl thus obtained, was 20%.

The results obtained in the polymerization of propylene with a catalyst formed from the TiCl are reported in Table 1.

Example 3 Example 1 was repeated, except that titanium trichloride used in this example was treated with 6% by weight of 2-ethyl-hexanol-1. The addition of alcohol was carried out under the conditions of Example 2. The amQ lm Qfi powder having a particle size smaller than 20 microns contained in the product was lower than 18%.

The results obtained by polymerizing propylene with the aid of the catalyst prepared from the treated delta crystalline TiCl are shown in Table 1.

As will be apparent, various changes in details may be made in practicing the invention, without departing from its spirit. Therefore, we intend to include in the scope of the appended claims all such modifications as will be ob- TABLE 2 Percent Isota Granulornetric distribution 01 the polymer in microns Percent in Apparent on the ticity (percent by weight) in powder density, catalyst index ($105 kg./l.

Example Type of alcohol added 21, 000 Z420 2177 2105 274 253 s 53 microns) 5 89 1. 3 17. 5 30. 13.9 8 6 8. 8 19.8 37. 2 0. 49 6 Isopropanol 5 90. 5 7 24. 2 30. 7 13. 8 5.8 4. 7 13. 8 24. 5 O. 55 7 Isopropanol plus 2-ethylhexanol. 4. 5 91 6. 3 19. 40. 8 14. 1 6. 8 4. 5 8. 5 19. 8 0. 55 8 2-ethylhexanol-1 5. 5 92 7 22. 5 27. 6 13. 8 6.3 6. 8 16 29. 1 0. 57 9 -.do 5. 5 92 6. 1 28. 4 28. 2 14. 2 6. 6 7. 7 8.5 8. 5 0. 57

Example 4 VlOllS to those skilled in the art from the description and Examples 5-9 The efiect of alcohols on the particle size and bulk density of the polymer was checked in industrial equipment (see Table 2).

In these runs, the alcohol was added, by means of a sprayer to the polymerization catalyst in a 2 me. homogenizer, equipped with stirrer and cooling jacket.

Example 8 was repeated (see Example 9) in order to check the reproducibility of the results.

Examples 10-12 Example 2 was repeated except that the delta 'A1Cl3 used in these examples was treated, under the conditions of Example 2, with the alcohols indicated in Table 3.

working examples given herein.

What We claim is:

1. A catalyst for the polymerization of olefins and prepared by mixing (a) an alkyl aluminum compound selected from the group consisting of AlR RgAlX and Al (C H Cl in which R is an alkyl radical containing 2 to 6 carbon atoms and X is halogen,

(b) a product containing titanium trichloride in the delta crystalline form, said product being obtained by homogenizing from 2 to 10% by weight of an alcoholic compound selected from the group consisting of monoand polyhydric aliphatic alcohols containing from 1 to 10 carbon atoms and such alcohols containing other functional groups with a preformed delta titanium trichloride prepared by drymilling a substance selected from the group consisting of alpha TiCl gamma TiCl mixtures of alpha and gamma TiCl cocrystallizates of alpha TiCl with AlCl cocrystallizates of gamma TiCl with AlCl and cocrystallizates of mixtures of alpha and gamma TiCl with A101 2. Catalysts according to claim 1, characterized in that the delta titanium trichloride used as component (b) contains as a result of contacting thereof with the alcoholic TABLE 3 Grauulometric distribution of the polymer in microns Percent Polymerization (Percent by weight) of Percent powder Apparent Type of alcohol on the Isotactic- ($105 density, Ex. (added) catalyst Activity ity index 21, 000 420 Z177 2105 274 253 553 microns) kg./l. 38 91.5 12.1 20.3 18.5 18.3 13.2 14 8.6 32.8 0.48 10. Ethylene glyeol 6 34 93. 5 l4. 5 24. 1 28. 8 12. 4 6. 4 5. 5 8. 3 20. 2 0. 49 11 Ethylene glycol 6 43 94. 5 14. 8 23. 2 26.6 13. 4 7. 8 11. 9 2. 3 22 0. 49

monophenylether. 12. Pentaerythritol 6 39 92. 5 15 24. 9 27. 2 12. 1 7 8. 8 5 20. 8 0.50

CHzO H (HO CHE--OHZOH) H1O H l The catalytic activity is expressed in g. polymer/g. 3TiCl -A1Cl hr. ata. 03'.

Examples 13-15 The 3TiCl -AlCl used in these examples was treated with the alcohols indicated in Table 4.

The polymerization conditions were the same as in Example 2. The titanium trichloride used in Example 15 was obtained by dry milling in a Locke mill for 3.5 hours an alpha and gamma 3TiCl -AlCl mixture to which 6% by weight of 2-ethylhexanol-1 was added.

TABLE 4 Polymerization Granulometrie distribution of the polymer in Percent of Percent Isotacmicrons (Percent by weight) powder Apparent on the ticity density, Ex. Type of alcohol added catalyst Activity 1 index 21,000 420 2177 2105 274 253 553 microns) kgJl. 13-.- Methanol 3 20 94 20. 5 32. 3 23. 9 l1. 2 5. 4 4 2. 7 12. l 0. 46 14.-." Diisopropylbenzenediol 6 43 93.5 11. 3 23.8 31. 1 13. 2 8.3 7. 5 4.8 20. 6 0. 54

(3H3 CHs 15.. 2-ethyl-hexano1'1 6 45 93. 1 10. 5 25. 1 27. 3 14. 6 10.2 8. 5 3. 8 22. 5 0. 46

1 Catalytic activity expressed in g. polymer/g. 3TiC1z-A1Cl3 hr. ata. Cr.

5. Catalysts according to claim 1, further characterized in that the alcoholic compound is selected from the group consisting of glycolmonoalkyl ethers and glycolmonoaryl ethers.

6. Catalysts according to claim 1, characterized in that component (b) is the product obtained by contacting the delta titanium trichloride with the alcoholic compound in the absence of a solvent.

7. Catalysts according to claim 1, characterized in that component (b) is the product obtained by contacting the alcoholic compound with the delta titanium trichloride suspended in an inert hydrocarbon solvent.

8. Catalysts according to claim 1, characterized in that component (b) is the product obtained by contacting the alcoholic compound with 3T iCl -AlCl obtained by reducing titanium tetrachloride with aluminum, and then transforming the reduction product into 3TiCl -AlCl in which the titanium trichloride is in the delta form, by dry-millmg.

9. Catalysts according to claim 1, characterized in that component (a) is a dialkylaluminum halide.

10. The process for the polymerization of higher alpha- References Cited UNITED STATES PATENTS 3,530,107 9/ 1970 Yoshioka et al. 26094.9 3,560,146 2/1971 Luciani et a1. 26094.9 3,130,005 4/1964 Siggel et al 26094.9 B 3,701,763 10/1972 Wada et al 260--94.9 C

JOSEPH L. SCHOFER, Primary Examiner EDWARD J. SMITH, Assistant Examiner US. Cl. X.R.

252--429 B, 429 C; 26094.9 C, 94.9 E

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3 793 295 Dated February 19, 1974 Inve t Luciano LUCIANI et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 5, line 5, Ti :1 should be Ti C13 Cols. 5 and 6, Table 2, under the heading 177, the last item 28. 2

should be 28.5

Cols. 5 and 6, Table 2, the heading "Percent in in powder 105 microns)" should be Percent in powder 105 microns last item under that heading, 8. 5 should be 22. 8

Col. 6, Claim l, line 6, the word with should appear after halogen,

Signed and sealed this 31st day of December 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN .Lttesting Officer Cosrmissioner 0 Patents USCOMM-DC 6037 6-P69 1' us. eovnuutut nmmnc emu; nu o-su-au FORM PO-105O (10 69) 

